This invention arose from frustrating inaccuracies inherent in prior art linear measurement interferometers. Although optical and electronic components in interferometers can function at a high level of precision, mechanical systems in prior art instruments considerably reduce the potential accuracy.
We have discovered a better way of arranging the elements and components of an interferometer to accomplish linear measurement with zero abbe error and an overall accuracy improvement over the prior art on the order of a factor of 10. Our interferometer is not only more accurate for several reasons, but is also compact, easily packaged and set up for operation, and adequately rugged so that it can measure accurately for a long time.